In order to extract ferromagnetic constituents retained in ores, the ore is ground and the powder obtained is mixed with water. This suspension is exposed to a magnetic field that is generated by a magnet or a plurality of magnets, so that the ferromagnetic particles are attracted and can thus be separated from the suspension.
A device for separating ferromagnetic particles from a suspension, in which a drum consisting of iron bars is used, is known from DE 27 11 16 A. The iron bars are alternately magnetized during the rotation of the drum, so that the ferromagnetic particles adhere to the iron bars, while other constituents of the suspension drop down between the iron bars.
A device for separating magnetic particles from an ore material in which the suspension is passed through a tube which is surrounded by a solenoid, is described in DE 26 51 137 A1. The ferromagnetic particles accumulate at the edge of the tube, other particles are separated by a central tube located inside the first tube.
A magnetic separator is described in U.S. Pat. No. 4,921,597 B. The magnetic separator has a drum on which is arranged a plurality of magnets. The drum is rotated in the opposite direction to the flow of the suspension, so that ferromagnetic particles adhere to the drum and are separated from the suspension.
A method for the continuous magnetic separation of suspensions is known from WO 02/07889 A2. Here a rotatable drum is used, in which a permanent magnet is mounted in order to separate ferromagnetic particles from the suspension.
With the known devices and methods there is sometimes the problem that sand and other unwanted constituents contained in the ground ore, which adhere to the ferromagnetic particles, are also separated, which is why the purity of the separated fraction of the ferromagnetic particles is inadequate.